曝光台 注意防骗
网曝天猫店富美金盛家居专营店坑蒙拐骗欺诈消费者
The spacing between taps can be changed by having different number of magnets
on the wheel. With a pitch of ¾-inch, a 6-foot2 area can be mapped out in less than
10 minutes with the magnetic wheel.
Figure 3 A magnetic cam drives the accelerometer (left) up and down as the wheel rolls over the area of
inspection.
In a tap test the contact time depends on the local stiffness of the part as well as
the mass of the impactor used. In the computer aided tap test system developed at
CNDE, a simple spring model is used to compute the local stiffness from the
measured contact time and the known mass of the impactor. The stiffness so
deduced from the tap test data is a meaningful mechanical property of the structure.
It was further demonstrated that the stiffness deduced from tap test and the
stiffness measured directly in a load test showed good agreement for a variety of
Page 3
Story of the Tapper
stiffness measured directly in a load test showed good agreement for a variety of
composites over a range of stiffness.
Over a period of three years, the composite group at CNDE has completed the
development of the Computer Aided Tap Test (CATT) system and applied it to a
wide range of composite materials and structures. It had been used on carbon and
glass composite control surfaces of aircraft, helicopter blades with Kevlar facesheet,
aluminum honeycomb sandwich with perforated skins, foam- and balsa-core boat
building structures, and adhesively bonded fiber boards. The system remained
simple and portable, as shown in figure 4, and has survived more than 15 field trials
at a number of airline maintenance facilities, aircraft manufacturers, and military
bases.
Figure 4 The Computer Aided Tap Test (CATT) system
Each test in the field has invariably led to some improvements in the software or
hardware. The development of the technique and the instrument has benefited
greatly from interactions with industry. Betasite tests were conducted at American
Airlines, Northwest Airlines (figure 5), United Airlines and the Royal Air Force (RAF).
The RAF has provided valuable human factors data for the system. Finally, this R&D
effort has also benefited substantially from the contribution of students. The
software development was done by Brian Danowsky and Nordica Hudelson , the
laboratory experiments were assisted by Zach Nielsen and Trent Simpson, and all
students have participated in field tests and gained real world experience.
For further information, contact Dave Hsu.
BACK TO TOP
Page 4
1
The Ice Particle Threat to Jet
Engines in Flight, and a New High
IWC Cloud Characterization Study
J. Walter Strapp
Environment Canada, Cloud Physics and Severe Weather
Research Division
Canada
2
Background
ARMP experience in cloud microphysics
measurements since mid-1970s – international
reputation
ARMP active in Aircraft Icing Projects since late
1980s – international reputation
ARMP active in study widening aircraft certification
envelopes since mid 1990s – IPHWG
This presentation results from our activities in
another form of aircraft icing research – jet-engine
icing
Canada
3
Jet-engine icing
• Since early 1990s, passenger-carrying jets (all sizes) have been
suffering engine powerloss events while flying near thunderstorms
• Engine events can range from momentary interruptions in power, to
full engine shutdowns that require a manual restart - Multiple engine
losses have occurred
• Thought to be related due to ingestion of high concentrations of ice
particles (ARMP and other analyses) – unconventional form of icing –
melting and refreezing in the engine
• ARMP worked with BAe Systems in the mid-1990s on BAe-146 jet
engine icing problem – now known to be industry wide
Canada
4
Cost and Safety
• Issue has caught the attention of Industry and Regulators –
committee (Engine Harmonization Working Group) formed to make
recommendations
• Damage to engines > $100K
• One 4-engine complete powerloss – engines turned back on 1500’
above the ocean
• One recent complete engine powerloss resulted in landing without
engine power in Florida
• FAA Icing Specialist has stated that they consider these events to be
the “precursor to a catastrophic accident”
Canada
5
Engine Harmonization Working
Group
• International Group to recommend to the Ice Protection
Harmonization Working Group a plan to remedy engine icing
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